fix(types): clear web/src type and lint debt with real types

tsc --noEmit and oxlint web/src are now both clean; vp check passes.

- htmx: one canonical Htmx interface in shims.d.ts (ajax/process/trigger
  per the htmx 2.x API). alpine.ts had a second, conflicting Window.htmx
  declaration (TS2717) — removed; bookPicker/collections lose their
  (window as any) escapes now that Window.htmx is properly typed.
- tsconfig lib ES2020 -> ES2021 + DOM.Iterable: replaceAll exists
  (escapeHtml) and for..of over querySelectorAll results is legal.
  Type-checking only — vite emits at esnext regardless.
- custom-section-builder: selectedBooks holds identity fields only;
  typed as Pick<BookInfo, ...> instead of forcing partial API shapes.
  The API-critical BookInfo contract is untouched.
- toast: real bug found by the type system — setup.ts passes 'warning'
  but getToastConfig had no entry, so the warning toast threw TypeError
  at runtime instead of displaying. Added the type + config. Uses
  bg-yellow-500 (verified present in scanned templates => generated by
  Tailwind); the one intentional behavior change in this commit.
- book-detail: instanceof narrowing replaces an as-cast; unused
  AnnotationSource import removed.
- password_validation: explicit HTMLElement | null for the checklist
  list (querySelector('ul') infers HTMLUListElement, conflicting with
  the container-as-list branch).
- stats: tooltip parsed value typed via annotation (bar=scalar,
  line={x,y}); dead getActiveRange() removed (was already tree-shaken
  out of every bundle).
- library-switcher: onSwitch honestly typed void | Promise<void>
  (series.ts passes a sync navigator).
- 20 unused catch bindings converted to optional catch binding.

Verification: fresh build is byte-reproducible; every chunk is
identical to the pre-fix build except main.js (instanceof narrowing,
regex fix, stats refactor), reader.js (destructure), and the shared
storage chunk (renamed — carries toast.ts). reader/main diffs audited
hunk-by-hunk against the intended edits.

web/src/stats.ts

@@ -151,11 +151,6 @@ function text(id: string, value: string): void {
   if (el) el.textContent = value;
 }
 
-function getActiveRange(): string {
-  const btn = document.querySelector(".stats-range-btn.btn-active") as HTMLElement | null;
-  return btn?.dataset.range || "7";
-}
-
 function markRangeButtons(active: string): void {
   document.querySelectorAll<HTMLElement>(".stats-range-btn").forEach((btn) => {
     const isActive = btn.dataset.range === active;
@@ -359,7 +354,9 @@ async function renderDailyCharts(daily: DailyEntry[]): Promise<void> {
       tooltip: {
         callbacks: {
           label: (ctx) => {
-            const v = typeof ctx.parsed === "number" ? ctx.parsed : ctx.parsed.y;
+            // Scalar for bar charts, {x, y} points for line charts.
+            const parsed: number | { y: number } = ctx.parsed;
+            const v = typeof parsed === "number" ? parsed : parsed.y;
             return `${Math.round(v * 10) / 10} ${unit}`;
           },
         },